Maths Qs from reader

Received an email from a reader. Please feel free to contribute your solution/ideas by posting in the comments section of this thread. Thank you.

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I am a Primary 6 Student and have been reading your blog since P5. I would like to ask for your help in the 2 questions from Pei Hwa Presbyterian CA1 Math paper:


Paper2
Q18:
7 apples cost $4
9 oranges cost $11
James bought a total of 1000 apples and oranges for $999.
How many apples and how many oranges did he buy?

Q5:
297 digits are used to print the page numbers of a story book.
What is the number on the last page number of the story book?

Please help me as I have spent so much time trying to find the answers and still can't.

Thank you so much and happy new year.

PSLE will start a week earlier this year

http://www.straitstimes.com/BreakingNews/Singapore/Story/STIStory_626701.html

THIS year's Primary School Leaving Examination (PSLE) will take place a week earlier to accommodate Children's Day.

The written papers have been scheduled for Sept 29 to Oct 5. Last year, they were held between Oct 6 and Oct 12.

The Ministry of Education (MOE) said in response to queries from The Straits Times that the adjustment was made to avoid disruption to the exam caused by the extended weekend to mark Children's Day.

Children's Day falls on Oct 7, a Friday, and will be celebrated the day before in schools, with many declaring half-days.

If the PSLE were to start in the first week of October, pupils sitting it would not be able to enjoy the long Children's Day weekend.

Last year, the MOE announced that Teachers' Day and Children's Day would be marked on the first Fridays of September and October respectively, starting from this year. This would give children and teachers long weekends in the two months.

Rosyth boy tops PSLE

http://www.straitstimes.com/BreakingNews/Singapore/Story/STIStory_607535.html

ALEX Tan Kian Hye of Rosyth School is the top Primary School Leaving Examination (PSLE) pupil this year with a score of 282.

Fu Wan Ying from Tao Nan School had the second highest score of 279.

The top Malay pupil is Aquilah Dariah Mohd Zulkarnain, of Coral Primary School who scored 278, while the top Indian pupil is Muhammad Hameem, of Henry Park Primary School with a score of 274, and the top Eurasian pupil is Lendermann Monika Jiz-xin, of CHIJ Our Lady Queen of Peace, with a 269 score.

Top PSLE 2010 Score - 282 (unofficial)

News from Kiasu Parents Forum.

Top Score - 282
School - Rosyth

Above is unofficial.

Year 2011 Classes

We are open for registration for the Year 2011

Classes and Subjects (Small group tuition)

Primary 1 and 2 - English, Maths
Primary 3 to 6 - English, Maths, Science

We will be starting classes early or mid November.


Taught by a husband and wife team.

Home based tuition, located at Tampines, along Tampines Avenue 5.

For enquiries, you may call Mrs Song at

6260 4258 or 9424 7940

Alternatively, you email us at - FreeMathSample@gmail.com

RGS Primary 2009 PSLE Math Prelim Paper 2 Q18

At first, 25% of Kumar's money was the same as 33 and 1/3 % of Lily's money. Lily's father gave her $80 later, while Kumar spent $325. In the end, Lily had 2 and 1/2 times as much money as Kumar.

a) How much money did Kumar have at first?

b) How much money did Lily have in the end?

Solution

(Kumar) 4 units --> 2 parts + 325 (x5)**

(Lily) 3 units + 80 --> 5 parts (x2)**

**Kumar (x5) and Lily (x2) to make both of them 10 equal parts each.

(K) 20 units --> 10 parts + 1625

(L) 6 units + 160 --> 10 parts

(K) 20 units --> 10 parts + 1625

(L) 6 units --> 10 parts - 160

(K) - (L)

20 units - 6 units --> 10 parts - 10 parts + 1625 - (-160)

14 units --> 1625 + 160

14 units --> 1785
1 unit --> 1785 divided by 14 = 127.5

(a)

Kumar at first

4 units --> 4 x 127.5 = 510

Answer: $510

(b)
Lily in the end
--> 3 units + 80
(3 x 127.5) + 80
= 382.5 + 80
= 462.5

Answer: $462.50

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RGS Primary 2009 PSLE Math Prelim Paper 2 Q17

At 9.30 am, Train A which was 200 m long, pulled out of Nanas Station and travelled towards Dadas Station at a uniform speed of 80 km/h. Half an hour later, Train B which was 150 m long, left Dadas Station and travelled towards Nanas Station at a uniform speed of 90 km/h.

a) How far has Train A travelled when Train B left Dadas Station?

b) The two trains met each other in a tunnel. Both trains took 15 minutes to completely travel through the tunnel. Calculate the length of the tunnel.

Solution

a)

Distance = speed x time

= 80 km/h x (1/2) hour

= 40 km

Answer: 40 km

b)

(Train A) distance

= 80 km x (1/4) hr

= 20 km

(Train B) distance

= 90 km x (1/4) hr

= 22.5 km

Length of Tunnel

--> 20km + 22.5km - 0.2km (Train A's length) - 0.15km (Train B's length)

= 42.15 km

Answer: 42.15 km

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RGS Primary 2009 PSLE Math Prelim Paper 2 Q16

There were some sweets in Boxes X, Y and Z. Box X contained 20% of the total number of sweets in Boxes X, Y and Z. The ratio of the number of sweets in Box Y to the total number of sweets in Boxes X and Z is 2:1. If there are 24 more sweets in Box Y than Box Z, find the total number of sweets in Boxes X, Y and Z.

Solution

Box X --> 20% of total sweets
= 20/100
= 1/5 --> (3/15) of total sweets

Box Y --> 2 units
Box X + Z --> 1 unit
(Total 3 units)

Box Y --> (2 units)/(3 units)
= 2/3 --> (10/15) of total sweets

Z --> 2 units
Y - Z --> 24 sweets
10 units - 2 units --> 24 sweets
8 units --> 24 sweets
1 unit --> 24 sweets divided by 8 = 3 sweets
15 units --> 15 x 3 sweets = 45 sweets

Answer: 45 sweets

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RGS Primary 2009 PSLE Math Prelim Paper 2 Q15

The equilateral triangles below are formed using 2 cm sticks.

a) How many sticks are needed to form Pattern 5?
b) In which pattern will each side of the triangle measure 30 cm?
c) Calculate the number of shaded triangles in Pattern 100.

Solution

b)
Pattern 1 --> 1 x 2cm = 2 cm
Pattern 2 --> 2 x 2cm = 4 cm
Pattern 3 --> 3 x 2cm = 6 cm
:
:
:
Pattern 15 --> 15 x 2cm = 30 cm

Answer: Pattern 15

From above
1 + 2 + 3 ..... + 100

1 + 99 = 100
2 + 98 = 100
3 + 97 = 100
:
:
49 + 51 = 100
(only 50 is not paired)

49 groups of 100 --> 4900
Add the unpaired 50 --> 4900 + 50 = 4950

Answer: 4950 shaded triangles

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RGS Primary 2009 PSLE Math Prelim Paper 2 Q14

John shifted the decimal point of a number twice to the left to obtain a new number. The difference between the new number and the original number was 136.62.

a) How many times the new number is the original number?

b) What is the sum of the 2 numbers?

Solution

a)

Answer: 100 times

b)

Original number --> 1 unit

New number --> 100 units

100 units - 1 unit --> 136.62
99 units --> 136.62

1 unit --> 136.62 divided by 99 = 1.38

Sum of the two numbers

--> 100 units + 1 unit = 101 units

101 units --> 101 x 1.38 = 139.38

Answer: 139.38

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